diff options
Diffstat (limited to 'gcc/cp/pt.cc')
| -rw-r--r-- | gcc/cp/pt.cc | 50 |
1 files changed, 38 insertions, 12 deletions
diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc index 1c1e573..2d83dfd 100644 --- a/gcc/cp/pt.cc +++ b/gcc/cp/pt.cc @@ -30408,6 +30408,26 @@ do_class_deduction (tree ptype, tree tmpl, tree init, cp_type_quals (ptype)); } +/* Return true if INIT is an unparenthesized id-expression or an + unparenthesized class member access. Used for the argument of + decltype(auto). */ + +bool +unparenthesized_id_or_class_member_access_p (tree init) +{ + STRIP_ANY_LOCATION_WRAPPER (init); + + /* We need to be able to tell '(r)' and 'r' apart (when it's of + reference type). Only the latter is an id-expression. */ + if (REFERENCE_REF_P (init) + && !REF_PARENTHESIZED_P (init)) + init = TREE_OPERAND (init, 0); + return (DECL_P (init) + || ((TREE_CODE (init) == COMPONENT_REF + || TREE_CODE (init) == SCOPE_REF) + && !REF_PARENTHESIZED_P (init))); +} + /* Replace occurrences of 'auto' in TYPE with the appropriate type deduced from INIT. AUTO_NODE is the TEMPLATE_TYPE_PARM used for 'auto' in TYPE. The CONTEXT determines the context in which auto deduction is performed @@ -30443,6 +30463,23 @@ do_auto_deduction (tree type, tree init, tree auto_node, auto_node. */ complain &= ~tf_partial; + /* In C++23, we must deduce the type to int&& for code like + decltype(auto) f(int&& x) { return (x); } + or + auto&& f(int x) { return x; } + so we use treat_lvalue_as_rvalue_p. But don't do it for + decltype(auto) f(int x) { return x; } + where we should deduce 'int' rather than 'int&&'; transmogrifying + INIT to an rvalue would break that. */ + tree r; + if (cxx_dialect >= cxx23 + && context == adc_return_type + && (!AUTO_IS_DECLTYPE (auto_node) + || !unparenthesized_id_or_class_member_access_p (init)) + && (r = treat_lvalue_as_rvalue_p (maybe_undo_parenthesized_ref (init), + /*return*/true))) + init = r; + if (tree tmpl = CLASS_PLACEHOLDER_TEMPLATE (auto_node)) /* C++17 class template argument deduction. */ return do_class_deduction (type, tmpl, init, flags, complain); @@ -30504,18 +30541,7 @@ do_auto_deduction (tree type, tree init, tree auto_node, } else if (AUTO_IS_DECLTYPE (auto_node)) { - /* Figure out if INIT is an unparenthesized id-expression or an - unparenthesized class member access. */ - tree stripped_init = tree_strip_any_location_wrapper (init); - /* We need to be able to tell '(r)' and 'r' apart (when it's of - reference type). Only the latter is an id-expression. */ - if (REFERENCE_REF_P (stripped_init) - && !REF_PARENTHESIZED_P (stripped_init)) - stripped_init = TREE_OPERAND (stripped_init, 0); - const bool id = (DECL_P (stripped_init) - || ((TREE_CODE (stripped_init) == COMPONENT_REF - || TREE_CODE (stripped_init) == SCOPE_REF) - && !REF_PARENTHESIZED_P (stripped_init))); + const bool id = unparenthesized_id_or_class_member_access_p (init); tree deduced = finish_decltype_type (init, id, complain); deduced = canonicalize_type_argument (deduced, complain); if (deduced == error_mark_node) |